This invention relates generally to a method and apparatus for forming a flange about one end of a can body.
In the manufacture of cans, one typical step in the process is to put on the ends. Part of the end-forming process usually includes the formation of a flange formed from the body material itself which is then utilized as a part of the interlocking mechanism with the can end closure. In the manufacture of typical metal cans, the flange is formed by a rolling process where the edge of the can body is bent by rollers outwardly at a suitable angle in order to form the flanged portion. This flanging process tends to result in nonuniformly formed flanges with wrinkles on the underside that can cause severe problems later when the end closure is formed. The wrinkles tend to result in a poorly formed closure. In addition, the known flanges forming methods and apparatus are limited in production quantities since a circumferential rolling process is required.
Similar problems occur when the can body is comprised of material other than metal such as a paper-plastic composite. When the roll flanging process is utilized, the application of the nonuniform forces results in wrinkles and thereby end closures that tend to be unreliable.
When contemplating an improved flange forming method and apparatus, it is important to consider the adaptability of any new apparatus to the general layout of the overall can manufacturing process. For example, it is typical that the rolled type flanging apparatus consists of a plurality of individual flanging devices mounted about a central column which rotates about a vertical axis. As the central column rotates, each individual device picks up a single can body and roll forms the flange as the entire assembly is rotated. It is not uncommon to have a plurality oftwelve such individual flange forming devices mounted about a central column, thereby greatly increasing the capacity. This general machine arrangement is common to the in-line can forming process and, if a faster flange forming process could be developed, ideally it should be mountable on a central column. Therefore, if the new flange forming process is speedier, then a twelve-unit system will produce more flanged can bodies than a comparable twelve-unit roll flanging system. Alternatively, fewer units could be mounted on the central column, thereby reducing the capital cost.
From the foregoing, one object of the present invention is to produce can bodies with uniformly formed flanges.
Another object of the present invention is to produce a flanged can body free from wrinkles in the material.
A further object of the present invention is to form uniform flanges at a high rate of speed.
Still another object of this invention is to provide a flange forming apparatus that is compatible with existing can manufacturing systems.
These and many other objects of the present invention will become apparent upon reading the specification to follow in conjunction with the attached drawings.